Ask for a scientific report, ask for a scientific inquiry report

During this summer, we conducted research on the conservation of mass in chemical reactions, and in this research, we deeply felt the charm of scientific research, and at the same time, we benefited a lot from this research. By designing the experiment, we have some conclusions and takeaways. I also have a deeper understanding of chemical reactions.

1. Design experiments.

Ask the question: After the decomposition of mercury oxide, is the mass of mercury produced and oxygen the same as that of the reactant mercury oxide?

Establish a hypothesis that after the decomposition of mercury oxide, the mass of mercury produced is equal to that of the mass of oxygen and the mass of the reactant mercury oxide.

Experimental equipment: test tubes, catheters, alcohol lamps, water tanks, iron frames, graduated cylinders.

Experimental drug: Mercury oxide.

Experimental principle: 2hgo 2hg+o2

Schematic diagram of the experimental setup: refer to the eight Zhejiang science books P131

Experimental Phenomenon: The solid disappears, bubbles are generated, and a silvery-white liquid is formed at the mouth of the test tube.

Experimental records: number of experiments Mercury oxide mass before heating Tube and drug quality before heating Tube and drug quality after heating Oxygen volume Oxygen quality.

1 52g 120ml

2 125ml

3 122ml

Experimental analysis: After three experiments, we obtained the above data. Analyzing this data, we found that:

Tube and drug quality before heating – Tube and drug quality after heating Oxygen quality, that is, the total mass before and after the reaction does not change.

Experimental conclusion: After the decomposition of mercury oxide, the mass of mercury and oxygen produced is equal to that of the reactant mercury oxide.

That is, in a chemical reaction, the sum of the masses of the substances involved in the chemical reaction is equal to the sum of the masses of the substances produced after the reaction.

Experimental reflection: In this experiment, the measured data deviated greatly from the ideal condition. Therefore, I checked the information and found that mercury can easily turn into mercury vapor when heated, which may be discharged from the catheter with oxygen, condense in contact with water, and mix with water, so the quality of the test tube and the drug will be small after heating.

After looking at the data, I found that reducing cuo with H2 is more suitable for proving the law of conservation of mass. This is because the products of this experiment are relatively easy to collect and have less error when collecting.

Physical Survey Report.

Experimental equipment: spring dynamometer, long wooden board, cotton cloth, towel, cuboid block with hook, weight, scale, stopwatch.

Experimental principle:1Condition for equilibrium of two forces: two forces acting on the same object, if they are equal in magnitude and opposite in direction, and are in the same straight line, the two forces are balanced.

2.Under the action of equilibrium force, the object at rest remains at rest, and the object in motion maintains a state of linear motion at a uniform speed.

3.When two objects in contact with each other are in relative motion or have a tendency to move relatively, a force will be generated on the contact surface that hinders the relative motion, which is called friction.

4.When the spring dynamometer pulls the wooden block to do a uniform linear motion on the horizontal plane, the magnitude of the tensile force is equal to the magnitude of the friction force, and the value of the tensile force can be read from the spring dynamometer, so that the friction between the wooden block and the horizontal plane is measured.

Experimental procedure: pull the wooden block at a constant speed with a spring dynamometer to make it slide along the long wooden board, so as to measure the friction between the wooden block and the long wooden board; change the weights placed on the block, thereby changing the pressure between the block and the long plank; Spread the cotton cloth on a long wooden board to change the roughness of the contact surface; Change the contact area by changing the contact surface of the block with the long plank.

Experimental data:1Pull the wooden block at a constant speed with a spring dynamometer to measure the friction between the wooden block and the long wooden board at this time

2.Add 50g of weights to the wooden block to measure the friction between the wooden block and the long wooden board at this time

3.Add 200g of weights to the wooden block to measure the friction between the wooden block and the long wooden board at this time

4.Lay cotton cloth on the wooden board and measure the friction between the wooden block and the long wooden board at this time

5.Speed up the speed of pulling the wooden block at a uniform speed, and measure the friction between the wooden block and the long wooden board at this time

6.Flip the block over so that another surface with a smaller area is in contact with the long plank, and measure the friction between the block and the long plank

If you verify Ohm's law, you can draw an image based on the data and use a calculator to fit the slope. ）

Conclusions:1The amount of friction is related to the pressure acting on the surface of the object, and the greater the pressure on the surface, the greater the friction.

2.The amount of friction is related to the roughness of the contact surface, and the rougher the contact surface, the greater the friction.

3.The amount of friction is independent of the area of the contact surface between the objects.

4.The magnitude of friction is independent of the speed of relative motion.

Error analysis and thinking: (This experiment is not, if you change the experiment to verify Boyle's law or something, you will have to write this piece.) ）